I had problems viewing the UI. Some of the text was missing and some would disappear when I scrolled over it. If I clicked Display in My Bitdefender nothing happened.
Also, viewing the logs was very hit and miss. Sometimes they would appear other times not.
Followed the advice of other posters and regularly had to exit and reload the UI in order to have a chance of viewing the logs.
Another problem was (when I was able to view the logs) I noticed that quick sweeps were carried out for about four days and then NOTHING.
Then I noticed that in CCleaner under Applications>Utilities there was an entry AntiVir Desktop. This obviously refers to Bitdefender.
Since unticking (unchecking) it the UI has improved 100%. If there is some text missing scrolling over it actually causes it to appear!
Have not had any problems in calling up the logs either and quick sweeps are showing for the last five days.
So, if anybody has the same problem and are running CCleaner (or a similar programme) I advise them to do the same.